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Depression outweighs other factors in worsening health

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VOL: 103, ISSUE: 38, PAGE NO: 21

Nerys Hairon

A study in The Lancet this month (Moussavi et al, 2007) reveals that depression has a greater effect on health than…


A study in The Lancet this month (Moussavi et al, 2007) reveals that depression has a greater effect on health than the long-term conditions angina, arthritis, asthma and diabetes. The study, based on World Health Organization figures, indicates that after adjustment for socioeconomic factors, depression has the largest effect on mean health scores compared with the other long-term conditions. It also found that the co-morbid state of depression ‘incrementally worsens health compared with depression alone, with any of the chronic diseases alone, and with any combination of chronic diseases without depression’.



The study authors emphasise the need for timely diagnosis and treatment of depression. Another study in the same issue of The Lancet focuses on unmet needs in the treatment of anxiety, mood and substance disorders (Wang et al, 2007).





The WHO studied 245,404 adults aged 18 and over from 60 countries to obtain data for health, health-related outcomes and their determinants (Moussavi et al, 2007). The researchers used ICD-10 criteria to estimate the prevalence of depression. The prevalence of the long-term conditions angina, arthritis, asthma and diabetes were also estimated. Mean health scores were compared across different disease states and demographic variables. The relation of disease states to mean health scores was determined through regression modelling.



Key findings


The one-year prevalence of an ICD-10 depressive episode alone was 3.2%; for angina it was 4.5%; for arthritis 4.1%; for asthma 3.3%; and for diabetes 2%.



An average of 9.3%-23% of participants with one or more long-term physical disease had co-morbid depression. For respondents with diabetes 9.3% also had depression, 10.7% of those with arthritis also had depression, 15% of those with angina had depression, and those with asthma had the highest prevalence of depression at 18.1%. For the 7.1% of respondents who had co-morbidity of two or more long-term physical conditions, nearly a quarter (23%) also had depression. The researchers state that the prevalence of depression in respondents with long-term conditions is ‘significantly higher than in respondents without chronic diseases’.



With regards to health scores, people without any of the long-term conditions or depression had the highest health score of 90.6 - that is, they reported having the best health. Those with asthma, angina, arthritis or diabetes alone had mean health scores of 80.3, 79.6, 79.3 and 78.9 respectively.



Participants with depression had the lowest health score among all the long-term conditions - 72.9. Those who had depression in combination with another long-term condition had much lower mean health scores than people with the long-term condition alone. For those who had two or more long-term conditions excluding depression, their mean health score was 71.8, lower than any of the disease conditions alone but higher than any disease state co-morbid with depression. The lowest overall mean health score was for people with two or more long-term conditions co-morbid with depression (56.1).



The authors say the results show that co-morbid depression - irrespective of age, sex and other demographic variables - is ‘significantly associated with lower health states in respondents with chronic conditions in comparison to having chronic conditions, including multiple chronic conditions, without depression’.



After controlling for all other factors, depression is associated with the lowest health scores, either alone or co-morbid with other long-term conditions. Depression co-morbid with diabetes causes greater decrements in health than the addition of the two conditions separately.



Research conclusions


The authors state that co-morbidity between depression and long-term physical conditions is common, and that people with long-term diseases are significantly more likely to have depression than those without. The data indicates that depression is associated with ‘a decrement in health that is significantly greater than those associated with the other chronic diseases in this study’.



The researchers explain: ‘Though depression has previously been shown to be associated with disability and declines in health-related quality of life, this is the largest-scale study to our knowledge that shows this decline using direct comparisons across physical conditions in multiple countries with a common measurement strategy.’



The authors conclude: ‘Our main findings show that depression impairs health state to a substantially greater degree than the other diseases. A significant percentage of respondents have depression in addition to their existing chronic physical conditions, a group that is often unrecognised and untreated.’



They argue that this finding is of special importance, as the detection of depression and its treatment is clearly related to the outcome of these long-term diseases. They describe the need for timely diagnosis and treatment of depressive disorders as ‘imperative’ to public health.



They add: ‘In many primary care settings, patients presenting with multiple disorders that include depression often don’t get diagnosed, and if they do, often treatment is focused towards the other chronic diseases. Depression can be treated in primary care or community settings with locally-available cost-effective interventions.’ They warn that depression is ‘a disease at least on a par with physical chronic diseases in damaging health’.



In a comment article accompanying the study in The Lancet (Andrews and Titov, 2007), two mental health experts speculate that better access to treatment may be one reason why disability is less with the physical disorders. ‘Treatment for depression should at least be on a par with that for other chronic diseases,’ they argue.





Nurses can help to improve patients’ overall well-being through improved detection and diagnosis of depression, and better management of long-term conditions. NICE has published guidelines on the management of depression in primary and secondary care for adults aged 18 and over (NICE, 2004, amended 2007), and on depression in children and young people (NICE, 2005).



One of the key priorities outlined in the guidance on depression in adults is screening in primary care and general hospital settings (see box below). Key priorities in the NICE guidance on depression in under-18s include detection and risk profiling, as well as recognition. See for full recommendations on all aspects of management.



In addition, the review of the GP Quality and Outcomes Framework led to new indicators being added for depression (British Medical Association, 2006). There are now 33 points for this condition.





The new research in The Lancet highlights the importance of recognising and managing depression as it is linked to worse health outcomes. The research also shows that people with long-term diseases are more likely to suffer from depression than those without.



For an example of how to improve the physical health of mental health service users, see the Development article on page 28 of this issue.





In primary care and general hospital settings, screen patients with:



- A past history of depression;



- Significant physical illness;



- Mental health problems such as dementia.



Healthcare professionals should bear in mind the potential physical causes and the possibility that depression can be caused by medication.



Use two screening questions, such as:



- During the past month, have you often been bothered by feeling down, depressed or hopeless?



- During the past month, have you often been bothered by having little interest or pleasure in doing things?



Source: NICE (2004).

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